過(guò)渡金屬氧化物三維納米結(jié)構(gòu)的組裝及其儲(chǔ)鋰性能研究
發(fā)布時(shí)間：2019-06-03 22:26
【摘要】：本論文主要針對(duì)傳統(tǒng)過(guò)渡金屬氧化物負(fù)極納米顆粒循環(huán)穩(wěn)定性差、堆積密度低和微米顆粒容量低、倍率差、循環(huán)差等關(guān)鍵科學(xué)問(wèn)題,提出通過(guò)簡(jiǎn)易的水/溶劑熱法組裝具有三維納米結(jié)構(gòu)的過(guò)渡金屬氧化物二次微米球型結(jié)構(gòu),合理調(diào)節(jié)組裝工藝,實(shí)現(xiàn)對(duì)顆粒形貌、尺寸、孔結(jié)構(gòu)和成分分布等性質(zhì)的有效控制,成功開(kāi)發(fā)了高容量、高倍率的針刺陣列型二元鎳鈷氧化物介孔微球負(fù)極材料和高倍率、長(zhǎng)循環(huán)和高安全性的成分梯度富錳三元鎳鈷錳多孔微球正極材料。具體研究?jī)?nèi)容如下:(1)以尿素為沉淀劑和自模板成功組裝得到陣列排布的針刺狀NiCo(OH)2CO3納米微球前驅(qū)體。經(jīng)過(guò)適當(dāng)調(diào)節(jié)空氣下前驅(qū)體的分解溫度,引入介孔結(jié)構(gòu),適當(dāng)降低比表面積,同時(shí)在長(zhǎng)大的一次顆粒中形成多相共存的相結(jié)構(gòu),電化學(xué)測(cè)試結(jié)果表明,在以上協(xié)同效應(yīng)的作用下,兩相共存的鎳鈷氧化物具有與純相Ni1.5Co1.5O4相當(dāng)?shù)谋堵市阅艿茄h(huán)性能獲明顯提高。(2)相比空氣下退火得到的兩相共存Ni1.5Co1.5O4,通過(guò)對(duì)針刺微球狀前驅(qū)體NiCo(OH)2CO3在N2氛圍下退火獲得針刺陣列介孔微球型低價(jià)態(tài)純相NiCoO_2同樣展現(xiàn)出優(yōu)異的倍率性能和相近循環(huán)性能,但是首圈不可逆容量降低了大約200 mAhg-1。(3)成功利用不同碳酸鹽沉淀在弱酸性條件下的溶解度不同構(gòu)建了具有富錳核心和三元?dú)拥某煞痔荻孺団掑i碳酸鹽微球型前軀體,并深入討論了抗壞血酸對(duì)碳酸鹽前軀體和氧化物中間體的形貌、組分、晶體結(jié)構(gòu)以及最終產(chǎn)物L(fēng)iNi0.2Co0.3Mn0.5O_2正極材料的電化學(xué)性能的影響。研究結(jié)果表明,在制備前驅(qū)體過(guò)程中加入抗壞血酸有助于獲得單分散性更好、二次顆粒更均勻細(xì)小、結(jié)構(gòu)更致密和成分梯度更和緩的LiNi0.2Co0.3Mn0.5O_2介孔正極微球,最終獲得具有優(yōu)異倍率性能、循環(huán)性能、熱穩(wěn)定性及高堆積密度的富錳梯度層狀三元氧化物正極材料。
[Abstract]:In this paper, the key scientific problems, such as poor cyclic stability, low stacking density, low micron particle capacity, poor doubling rate and cycle difference, are mainly discussed in the traditional transition metal oxide negative electrode nanoparticles, such as poor cyclic stability, low stacking density, low micron particle capacity, low doubling rate, poor cycle and so on. It is proposed that the secondary micron spherical structure of transition metal oxide with three dimensional nanostructure can be assembled by simple water / solvothermal method, and the assembly process can be adjusted reasonably to realize the effective control of particle morphology, size, pore structure and composition distribution. High capacity and high rate of acupuncture array binary nickel cobalt oxide mesoporous microspheres negative electrode materials and high rate, long cycle and high safety component gradient manganese rich ternary nickel cobalt manganese porous microspheres cathode materials were successfully developed. The specific research contents are as follows: (1) using urea as precipitant and self-template to successfully assemble the array arrangement of needle-like NiCo (OH) 2CO3 nanoparticles precursor. After properly adjusting the decomposition temperature of the precursor in the air, introducing the mesoporous structure, properly reducing the specific surface area, and forming the multiphase coexistence phase structure in the growing primary particles, the electrochemical test results show that, Under the above synergistic effect, the two-phase coexisting nickel-cobalt oxide has the same rate performance as pure phase Ni1.5Co1.5O4, but the cyclic performance is obviously improved. (2) compared with the two-phase coexisting Ni1.5Co1.5O4, obtained by air annealing The needle array mesoporous microsphere type pure phase NiCoO_2 was obtained by annealing the acupuncture microspherical precursor NiCo (OH) 2CO3 in N2 atmosphere. The pure phase NiCoO_2 also showed excellent doubling performance and similar cyclic performance. However, the irreversible capacity of the first cycle decreased by about 200 mAhg-1. (3) the composition gradient nickel cobalt manganese carbonate with rich manganese core and ternary shell was successfully constructed by using the different solubility of different carbonate precipitation under weak acid conditions. Salt microsphere precursor, The effects of ascorbic acid on the morphology, composition, crystal structure and electrochemical properties of the final product LiNi0.2Co0.3Mn0.5O_2 cathode materials were also discussed. The results show that the addition of ascorbic acid in the preparation of precursors is helpful to obtain LiNi0.2Co0.3Mn0.5O_2 mesoporous positive microspheres with better monodispersion, more uniform and fine secondary particles, denser structure and more gentle composition gradient. Finally, manganese-rich gradient layered ternary oxide cathode materials with excellent doubling performance, cyclic property, thermal stability and high stacking density were obtained.
【學(xué)位授予單位】：南京郵電大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2017
【分類(lèi)號(hào)】：TB383.1;TM912
本文編號(hào)：2492269
[Abstract]:In this paper, the key scientific problems, such as poor cyclic stability, low stacking density, low micron particle capacity, poor doubling rate and cycle difference, are mainly discussed in the traditional transition metal oxide negative electrode nanoparticles, such as poor cyclic stability, low stacking density, low micron particle capacity, low doubling rate, poor cycle and so on. It is proposed that the secondary micron spherical structure of transition metal oxide with three dimensional nanostructure can be assembled by simple water / solvothermal method, and the assembly process can be adjusted reasonably to realize the effective control of particle morphology, size, pore structure and composition distribution. High capacity and high rate of acupuncture array binary nickel cobalt oxide mesoporous microspheres negative electrode materials and high rate, long cycle and high safety component gradient manganese rich ternary nickel cobalt manganese porous microspheres cathode materials were successfully developed. The specific research contents are as follows: (1) using urea as precipitant and self-template to successfully assemble the array arrangement of needle-like NiCo (OH) 2CO3 nanoparticles precursor. After properly adjusting the decomposition temperature of the precursor in the air, introducing the mesoporous structure, properly reducing the specific surface area, and forming the multiphase coexistence phase structure in the growing primary particles, the electrochemical test results show that, Under the above synergistic effect, the two-phase coexisting nickel-cobalt oxide has the same rate performance as pure phase Ni1.5Co1.5O4, but the cyclic performance is obviously improved. (2) compared with the two-phase coexisting Ni1.5Co1.5O4, obtained by air annealing The needle array mesoporous microsphere type pure phase NiCoO_2 was obtained by annealing the acupuncture microspherical precursor NiCo (OH) 2CO3 in N2 atmosphere. The pure phase NiCoO_2 also showed excellent doubling performance and similar cyclic performance. However, the irreversible capacity of the first cycle decreased by about 200 mAhg-1. (3) the composition gradient nickel cobalt manganese carbonate with rich manganese core and ternary shell was successfully constructed by using the different solubility of different carbonate precipitation under weak acid conditions. Salt microsphere precursor, The effects of ascorbic acid on the morphology, composition, crystal structure and electrochemical properties of the final product LiNi0.2Co0.3Mn0.5O_2 cathode materials were also discussed. The results show that the addition of ascorbic acid in the preparation of precursors is helpful to obtain LiNi0.2Co0.3Mn0.5O_2 mesoporous positive microspheres with better monodispersion, more uniform and fine secondary particles, denser structure and more gentle composition gradient. Finally, manganese-rich gradient layered ternary oxide cathode materials with excellent doubling performance, cyclic property, thermal stability and high stacking density were obtained.
【學(xué)位授予單位】：南京郵電大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2017
【分類(lèi)號(hào)】：TB383.1;TM912
【參考文獻(xiàn)】
相關(guān)期刊論文 前2條
1 張宏明;史新明;趙陽(yáng)雨;毛麗萍;崔孝玲;;鋰離子電池新型正極材料研究展望[J];電源技術(shù);2013年10期
2 鄭子山,張中太,唐子龍,沈萬(wàn)慈;鋰離子二次電池最新進(jìn)展及評(píng)述[J];化學(xué)世界;2004年05期
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